The present invention is directed to determining a transformation (a matching transformation) which (in particular non-rigidly) matches a set of one or more images of an anatomical body structure of a human or animal patient and a set of one or more images of a general anatomical structure of a patient model as described by an anatomical atlas, by matching respective images of the sets to each other, in particular using image fusion, wherein the respective images are associated with the same parameter set (see below) and represent one or more anatomical elements which are matched to each other and correspond to each other.
The anatomical atlas (or “atlas” for short) describes the general anatomical structure of the complete body of a patient model or an object in the patient model or in particular a plurality of objects in the patient model which in particular have a defined positional relationship with respect to each other. An object can comprise one or more anatomical elements. The atlas can be a two-dimensional or three-dimensional (static) atlas or a time-dependent two-dimensional or three-dimensional atlas (a so-called 4D atlas).